LONDON — With a blend of rose-glow nostalgia and incredulity, some baby boomers of a certain vintage here recall vacations in Europe long ago when the sight of a rare British license plate on the arrow-straight roads of northern France inspired much waving and tooting of horns in mutual recognition.

In those times, they will say, Britons emerging from the gloom of postwar austerity discovered a land of pungent cigarettes and fine cuisine, vin ordinaire and menus du jour that titillated palates grown stale on bland and rationed British fare.

There were time-consuming border crossings, too, and sharp-eyed customs agents; currency controls; carnets de passage; and coupons that permitted outsiders to purchase gasoline, sometimes in villages with hand-pumps that recalled much earlier technologies.

Decades later, Europe has ironed out many of its idiosyncrasies. No one waves anymore. Border controls have largely disappeared. The clothing chains offer the same brands in London, Paris, Madrid or Berlin. With the possible exception of military veterans visiting the erstwhile battlefields of loss and glory, the novelty of returning in peace to the loci of war has faded.

Yet, as Britain prepares for a referendum on June 23 on whether to remain in the European Union, it is perhaps worth recalling that its ties to the great landmass beyond the channel long predate the bloc’s establishment as a huge trading zone, creating bonds that will not easily dissolve.

Long before the first British Austins and Morris Minors ventured across a choppy channel to joust with French Citroëns and Renaults, British artists and poets — Turner and Keats, Byron and Shelley — drew inspiration in Italy, France or Switzerland.

In the automobile age, well-heeled travelers in their elegant touring cars sought out the bright lights of Paris and the gambling tables of Monte Carlo.

Even earlier, in Nice, the Promenade des Anglais, an elegant walkway along the Mediterranean, took its name from Britons wintering there in the 19th century. In Munich, the vast Englischer Garten dates to the late 18th century.

These days, some 1.3 million Britons live on the Continent, according to the United Nations, seeking work or sunshine. Many more have second homes there. Even Nigel Lawson, a leader among British Conservative politicians clamoring for withdrawal from the European Union, maintains a residence among the expatriates of southwestern France.

Such tangled ties go some way toward explaining why the referendum has divided opinion so fiercely here, permeating public debate with mutually exclusive arguments on everything from border controls and migration to the shape of bananas.

The distinctions slice across the generations, with surveys showing that the young, less inclined to leave the bloc, are also less likely to vote, while the aged, keener to leave, are also more energetic voters.

In some ways, it is surprising that the divide between the two camps remains so stubbornly even. That suggests, perhaps, that for half the population, nostalgia is defined more by a hankering for a go-it-alone Britain to regain a possibly apocryphal notion of self-reliance outside the European Union than by any recollection of shared history — and certainly not by tooting car horns or people with very long memories.

This week, the Supreme Court here ruled in favor of regulations forbidding up to two million Britons who have lived abroad for more than 15 years from voting. (Paradoxically, those permitted to vote include an estimated one million British residents who are citizens of Ireland or of the 53 countries in the Commonwealth, made up largely of onetime imperial possessions.)

And now to (almost) full disclosure: As a baby boomer whose family Austin once crisscrossed Continental Europe at a dogged 55 miles per hour, I am among the millions eligible to vote. But, in advance, I no longer wave to my compatriots to coax a signal of shared identity, preferring to ask the minefield question du jour: Which side are you on?